NLM provides technical assistance and troubleshooting support for the 50,000+ users and 40+ databases available on NLM's MEDLARS system. Assistance may be obtained by calling a toll-free 1-800 number for the MEDLARS Service Desk. The MEDLARS online system is available 24 hours a day, around the clock. Many physicians and other health professional searchers who use the Grateful Med software interface typically search during evening hours and frequently need support after 5:00 p.m. E.T The primary objective of this contract is t obtain contractor support to provide telephone user assistance during extended Service Desk hours of operation (i.e., 5:00 pm - 12 Midnight ET, M-F and Saturdays, 8:30 am - 5 pm ET). The contractor staff will actually be providing service M-F beginning at 3:30 pm to help relieve current staff from so many hours of Service Desk duty. The support will be performed in the same manner as regularly provided by MMS staff from 8:30 am - 5 pm M-F. Contractors staff will serve, one person at a time, on the Desk providing assistance and technical troubleshooting on various systems; databases; telecommunications software and networks; gateways; Grateful Med installation problems, telecommunications SETUP assistance, search advice, etc.; MEDLARS command language searching, search strategy construction, and Medical Subject Headings search vocabulary; IBM PC and DOS operations; Macintosh and System 6/7 operations; and other biomedical database, technical computer and information storage and retrieval issues where complex user support problems can be both subtle to diagnose and difficult to resolve.